> As I understand, the downloadable cd image is ISO format and not bootable. 
> The actual bootable image is on the CD called diskimage.gz.  But nowhere 
> there is a documentation tell you how to burn this image to cd and make it 
> bootable for SGI machine.

I had made a bootable NetBSD/sgimips CD-ROM on NetBSD/sgimips not IRIX.
The document <URL:http://www.netbsd.org/Documentation/bootcd.html> does
not explain how to make it.

ex.

mkdir -p /path/to/cdsources
cd /path/to/cdsources
ncftpget ftp://ftp.netbsd.org/pub/NetBSD/NetBSD-1.6.1/sgimips/binary/kernel/netbsd-INDY_INSTALL.gz
gunzip netbsd-INDY_INSTALL.gz
mv netbsd-INDY_INSTALL netbsd
chmod 555 netbsd
mkdir -p /path/to/cdsources/sgimips/binary/sets
cd /path/to/cdsources/sgimips/binary/sets
ncftpget -R ftp://ftp.netbsd.org/pub/NetBSD/NetBSD-1.6.1/sgimips/binary/sets/
chmod 444 *
find /path/to/cdsources -type d -exec chmod 755 {} \;
chown -R root:wheel /path/to/cdsources

dd if=/dev/zero of=/path/to/sgimips.img bs=512 count=200k
vnconfig vnd0 /path/to/sgimips.img

vi /path/to/disktab
	sgimips-cd:\
		:ty=vnd:se#512:ns#32:nt#1:sc#32:nc#6400: \
		:pa#200704:oa#4096:ta=4.2BSD:ba#8192:fa#1024: \
		:pc#204800:oc#0:bb#0:fb#0: \
		:pd#4096:od#0:td=boot:
disklabel -w -f /path/to/disktab vnd0 sgimips-cd

/usr/mdec/sgivol -w boot /usr/mdec/boot.elf vnd0

newfs vnd0a
mount /dev/vnd0a /mnt
cp -pr /path/to/cdsources/* /mnt

cdrecord -v speed=12 dev=1,6,0 /path/to/sgimips.img

umount /mnt
vnconfig -u vnd0
rm -rf /path/to/cdsources /path/to/disktab /path/to/sgimips.img

-- ayamura